Government-backed pseudo-anonymous cryptocurrencies? With no possibility of blocking accounts or taking money from users whenever they want, or monitoring you whenever they want? Hahahaha. Not gonna happen. Never-ever-ever-EVER.
This is like saying in the middle ages: "Democracy? An elected king whose actions can be punished by the population? Not going to happen"
If the population of a country demands it unanimously (I'm not saying this is likely to happen, at least not soon), the government has no other choice.
But let's analyze the potential advantages for the government when issuing a national coin.
Let's say the currency is like bitcoin but with centralized issuance (like beertokens or usdCoins) directly by the state (without a central bank that also charges interest to the state that legitimize it).
Yes, they lose control over it. But regular cash also doesn't enforce the payment of VAT and enables its use for illegal activities.
The decentralized management of a currency is desirable for its users. If say, Greece decides to issue drachmaCoin, that would be the first national currency tradeable for bitcoins in a decentralized manner and would share other advantages for the users with bitcoin (smart property, contracts, etc). More people other than greeks (who would be forced) would use those drachmaCoins and that is good for the country.
In the end, when you hold national currency you're holding IOUs from the state. But those IOUs are not redeemable for anything apart from paying taxes and the state doesn't have to pay interests on this "debt issuance".
If foreign investors hold a billion of DRC, that's great for Greece. The state is printing but the price inflation is being exported (or absorbed by foreign investors).
Certainly they would be better than with the Euro.
Also, the state outsources the costs of management of the currency to miners. Miners can live on fees or be perpetually rewarded a la expocoin/freicoin. And still the state can enjoy its monopoly on discretionary printing.